Contra-flow ventilating apparatus



1965 L. M. STIRLING 3,199,773

CONTRA-FLOW VENTILATING APPARATUS Filed Oct. 14, 1963 2 Sheets-Sheet lINVENTOR 2 0 M. STIRLIE I ATTORNEY Aug. 10, 1965 1.. M. STIRLINGCONTRA-FLOW VENTILATING APPARATUS 2 Sheets-Sheet 2 Filed Oct. 14, 19631", n, INVENTOR 53 /65 5% Leo M. STIRLING ATTORNEY United States Patenttea! 3,1,773 CQNTRA-FLGW VENTILATING APFARATUS Leo M. Stirling, 546iQranbroohe Ava, Montreal, Quebec, Canada iled Get. 14, 1963, tier. No.315,967 6 Elairns. (El. 239-117} The present invention relates to themanufacture of fans and more particularly to the manufacture of fansparticularly suited for use in industrial air circulation, ventilating,air conditioning and heat transfer installations.

The type of fan which the present invention is concerned is that whichprovides contra-flow air currents in a single unit permitting the doublefunction of exhausting and introducing air in a ventilating system. Forexample, this type of fan is illustrated and described in detail in theapplicants United States Patent 2,790,596, issued April 30, 1957. Inthis construction, means are provided in the form of a single fanassembly to create a parallel fiow of air in opposite directions throughthe use of a first series of fan blades extending from a central hubwith an annular rim surrounding the outer tips of the first blade setand serving as a hub for a second series of blades. The first and secondseries of blades are arranged concentrically and are disposed so as tobe inclined in the same plane but in opposite directions.

The present invention aims to provide an improved construction of aventilation fan of this type and for this purpose has designed acontra-flow fan arrangement which utilizes a direct drive to actuate afirst bladed fan wheel to move the air in one direction and a secondseries of fan blades connected directly to the fan wheel and adapted tomove the air in an opposite direction.

The mounting and arrangement of these air moving elements is such thatthe overall dimensions, when compared with the earlier constructionmentioned above, are considerably reduced while the capacity of theventilating unit is at least equal to or increased over that of acomparable unit of the earlier type. In the present construction, thedirect drive is applied along the axes of the fan units and the secondseries of fan blades is offset axially relative to the first fan wheelso that the external diameter of the combined fans is no greater thanthat of the fan wheel. This means that the internal ducting separatingthe air flows and the drive for the fans can be entirely containedwithin a cylindrical housing making a more compact assembly than waspossible with the earlier construction.

A further feature or" the present construction resides in the provisionof a damper system which is also fully contained within the unit casingand which is constructed so that the flow of air in opposite directionscan be controlled to provide a proportioned supply-exhaust air ratio asrequired. This is accomplished by mounting two sets of damper blades inconcentric relationship within the inner and outer duct portionscontrolling the contra-flow of air of the fan blades and providing meanswhereby these damper blades can be rotated in a shutter like action tocontrol the respective air flows. In one preferred construction, themovement of the inner and outer damper blades is linked so that bymoving a controlling lever in one direction the inner damper blades willclose and the outer damper blades will open an equivalent amount or viceversa. In an alternative arrangement, independent controls can beprovided to each set of damper blades if so desired.

Having thus generally described the nature of the invention, particularreference will be made to the accompanying drawings, showing by way ofillustration preferred embodiments thereof, and in which;

3,l9i9,773 Patented Aug. 10, 1955 FIGURE 1 is a view in front elevationshowing a direct drive dual air stream ventilator with controlleddampers in accordance with the invention.

FIGURE 2 is a view corresponding to FIGURE 1 with portions of the casingshown in section to illustrate the fan blading arrangements moreclearly.

FIGURE 3 is an enlarged cross sectional view of the construction ofFIGURES 1 and 2 to illustrate the air flow paths and damper bladecontrol arrangement in more detail.

FIGURE 4 is an enlarged horizontal cross section of the constructionshown in FIGURE 1 as seen along the line 4-4 of FIGURE 1.

FIGURE 5 is a cross sectional view of FIGURE 4 along the line 5-5 toillustrate the mounting of the damper blades in more detail.

FIGURE 6 is a sectional view of the construction of FIGURE 4 as seenalong the line 66 to show the relative position of inner and outerdamper blades with the outer blades in closed position.

FIGURE 7 is a sectional view corresponding to FIG- URE 6 to illustratethe relative position of the damper blades with the inner blades inclosed position.

FIGURE 8 is a sectional view of FIGURE 4 as seen along the line 83 toillustrate the gearing arrangement between the damper blades.

FIGURE 9 is a sectional view of a segment of the inner and outer damperblades as they would appear in an alternative arrangement permittingseparate adjustment or" inner and outer blades.

FIGURE 10 is a sectional view of the construction of FIGURE 9 along theline 1tl10 to illustrate a preferred arrangement for connecting theouter blades for controlled movement independently from the innerblades.

With particular reference to FIGURES 1 and 2 of the drawings, a dualfiow fan construction, in accordance with the invention, consists of amain casing and supporting frame It wherein there is mounted for adirect drive from a motor 12, a first fan wheel assembly 14 to whichthere is connected a second blade assembly 16, as shown most clearly inFIGURE 3. In this construction, the fan wheel 14 is bladed so as to drawthe air upwardly through its centre portion and expel the air from aboutthe periphery while the blades of the assembly 16 are inclined in adirection to move the air downwardly in the opposite direction. It willbe appreciated that driving arrangements other than that shown could beutilized, for example, the motor 12 could be offset from the axis of thedevice and a belt drive could be utilized.

As shown, the casing it; is made up of a base portion 2% ofsubstantially annular formation with an exterior duct portion 22.fitting concentrically of the base 25 and being attached thereto bysuitable welding or the like. A plurality of upright cylindricalstandards or supporting rods 24 are mounted on the base 20 incircumferentially spaced relationship and these are utilized to supportan annular air deflecting flange 26 and a casing top 28 of dome-likeconfiguration. The casing top 28 is provided with a plurality oflouvered openings 3% about its outer circumference and an outstandingannular flange 32 by means of which it is assembled to the casingsupports 24. In the construction illustrated, a circular motorsupporting plate 34 is provided and the motor 12 is mounted centrally ofthis plate on rubber mounts 38 providing an air space 39 beneath themotor. This air space 3? allows some of the air sucked into the casingtop 28, through the drop in pressure created by the main exhaust flowcreated by the fan Wheel 14, to fiow under the motor during itscirculation passage thus ventilating the motor. The air sucked into thecasing top 28 also serves to cool and ventilate the motor and to preventpossible accumulation of exhausted gases within the casing top, forexample exhausted gasses which might be explosive and, therefore,dangerous if permitted to accumulate in a motor containing enclosure.

The preferred fan wheel assembly 14illustrated is of a type known to thetrade as a backwardly curved wheel and the tapered blades or vanes aremounted between a flat backing plate 40 and an inwardly flaring annularcollar 42. The second set of blades 16 are mounted in regularcircumferentially spaced relationship about the lower portion of theannular collar 42 so as to be in concentric relationship with the wheelassembly 14 and offset axially by reason of the inward flare of thecollar 42 so that the outer periphery of the blades 16 is substantiallyequal to the outer diameter of the wheel 14. The backing plate 49 isprovided with a centrally located shaft attachment fitting 44 to whichthe shaft 13 of the motor 12 is secured so that in the constructionshown the complete rotating assembly of wheel 14 and blades 16 aresupported by and driven directly from the motor 12.

In order that the contra-flowing air currents are correctly directed,the lower inner portion of the deflecting flange 26 fits closely to, butdoes not contact, the annular collar 42 of the wheel assembly 14. As isshown .most clearly in FIGURE 3, the blades of the assembly videclearance for the lower end of the annular collar 42 to which the blades16 are mounted.

As shown in plan in FIGURE 4, the damper assembly of the presentdual-flow ventilator of the invention is 'mounted concentrically of thecasing and is adapted to control the air flow passing through the inner23 and outer 22 duct portions under the action of the fan wheel 14 andblade assembly 16. As previously mentioned, damper supporting shafts 59extend radially inwards from the exterior of the duct portion 22 toadjacent the centre of the inner duct 23 and a first series of damperblades 52 are mounted on the shafts 56 to control the flow through theduct portion 23 and a second series of damper blades or vanes 54 aremounted on the shafts 5% to control the flow through the outer ductportion 22.

In the construction illustrated, the blades 52 are segment-shaped anddimensioned so that when rotated into duct blocking position the sideportons of each blade are only slightly spaced from the side portions ofthe adjacent blades so as to almost completely block the flow of air.

The blades or vanes 54 are not symmetrical and are dimensioned so that aportion of the side margins of each blade overlaps a correspondingportion of the adjacent blades to provide the maximum blockage and toprevent the blades 54 from being rotated beyond fully closed position.As is shown most clearly in FIGURE 5, for example, the inner ends of theshafts 50 are connected into a central hub and gear casing 69 which isin two parts 60a, 6012 held together by a bolt 62 which also serves asthe retaining means for a shaft end support 64 and an axis for aplanetary type bevel gear 6-6. A bevel gear 68 is mounted on the end ofeach shaft 50 journalled in the support 64 and all of these gears 68 arein meshed engagement with the main gear 66. With this arrangement,rotation of any of the shafts 50, in the present construction the shaft50a, causes a corresponding rotation of the remaining shafts on whichthe damper blades are mounted. For the purpose of providing a meansconnectable to an exterior control means either mechanical orelectrical, the outer end of the shaft 50a is provided with an offsetlever extension 58. In the preferred construction presently described,the blades 52 and the blades 54 are secured to the shaft 50 atsubstantially 90 to each other so that when one set of blades is set atfull damping position, the other set is at full open position with anyintermediate setting being the same. With this arrangement, any desiredsupply-exhaust air ratio can be obtained by movement of a singlecontrol.

In the event that it is desired to provide means for separate control ofexhaust and/ or supply with respect to the damping mechanism, theconstruction would be altered slightly in that the shafts would extendradially inwards as before with the inner blades 152 secured to theirrespective shafts but the mounting of the blades 154 would be on tubularsleeves which in turn would freely fit 'over the shafts 150. Each blade154 would be shaped centrally to provide opposing semi-circular segments153a, 153b which fit over the sleeve 165 and retained thereto byretaining screws 166, see FIGURES 9 and 10. The tubular sleeves 165 areof sufficient length to extend outwardly of the duct portion 22 and eachsleeve end provided with an offset lever extension 167. In thisconstruction, all the lever extensions 167 would be interconnected to acommon control ring (not illustrated) so that rotary movement of thering would cause a simultaneous and corresponding opening or closingmovement of the'blades 154 independently of the controlling movements oflever extensions 15S and the shafts 150 which would now act only on theblades 152.

In operation, the dual-flow ventilator of the invention would bemounted, say for example on the roof of a building with the base 20securely mounted over a suitable opening. The inner and outer portions23, 22 would be connected to suitable additional ducting leading to theportion of the building or apparatus within the building to beventilated. When placed in operation by the starting of the motor 12,the flow of intake and exhaust air would follow opposed flow paths asindicated by the arrows in FIGURE 3, ie the main air supply or intake asinduced by the blade assembly 16 would be drawn into the annular spaceSt between the duct portions 22, 23 under the directing deflection ofthe lower flange of the member 26 which, with the inwardly conveyingportion of the annular collar 42, also acts to baflle the supply flowfrom the exhaust flow passing upwardly through the inner duct portion23. At the same time, a further supply of ventilating and cooling air isdrawn in through the louvered openings 30 on the casing top portion 28and is circulated about the motor 12 and exhausted into the main exhauststream through a shaft accommodating opening 33 in the motor supportingplate 34.

The casing intake flow referred to is created by the drop in pressurewithin the casing top caused by the main exhaust discharge from theperiphery of the fan wheel 14 emitting from between the motor supportingplate 34 and the annular deflecting member 26. The rotation of the fanwheel 14 draws the exhaust air up into the central portion of the wheel14 and through the inner duct portion 23. As will be appreciated byreference to the preceding description and accompanying drawings, thediameters of the inner and outer ducts 23, 22 can be selected to give asubstantially balanced supply-exhaust flow capacity and this in turn canbe readily controlled by the damper arrangement of the invention to anydesired intermediate supply-exhaust ratio. The simple compact design ofthe present dual-flow ventilator, embodying a direct drive eliminatingany driving chains or belts, a minimum of easing elements to separateand guide the contra-flowing air streams, and the reduction in overalldiameter and height of the present combined fan wheel and opposing fanblade assembly as well as the concentric double damper arrangementprovides constructional and installation advantages not found in theprior art ventilator constructions of this general nature.

Further, as the present fan construction has no hearings or motor in theair stream, it can be used to exhaust highly corrosive gases or hightemperature without any modifications. In such applications, damperscould be deleted as it is obvious that the whole unit could be suppliedwithout air control damper if desirable. In this case, of course,

means other than the illustrated damper blade supporting shafts shownwould be utilized to support the inner duct portion, for example, afixed supporting spider could be utilized.

I claim:

1. A contra-flow ventilating fan assembly adapted for use in industrialair circulating systems comprising, a first fixed cylindrical airconducting outer casing of constant diameter, a second fixed cylindricalinner casing of lesser diameter than said outer casing mounted to andconcentrically of said outer casing, said inner casing being of slightlylesser length than said outer casing and having one end disposed belowthe corresponding end of said outer casing, a contra-flow fan bladeassembly mounted in axial alignment with and above said inner and outercasings, means to support said fan assembly, a flat top plate and aninwardly tapering bottom collar of annular formation, said fan assemblyhaving a first fan wheel having fixed tapered fan bla des extendingradially inwards between said fiat top plate and said inwardly taperingbottom collar of annular formation, and a second set of fan bladesmounted at the roots to said fan wheel annular collar so as to extendradially outwards therefrom and being inclined whereby when rotated withsaid fan wheel to cause a movement of air in a direction opposite tothat caused by said fan wheel blades, means supporting said innercylindrical casing concentrically of and relative to said outer casingpermitting free rotation of said second fan blade assembly within anannular space between said inner and outer casings, driving meansincluding a driving motor partitioned from and mounted directly abovesaid contraflow fan assembly with a connection to said first fan wheel,a fixed annular air flow deflecting means surrounding said fan wheel andhaving a portion extending inwardly between the outer periphery of saidfan wheel and the blades of said second blade assembly thereby beingadapted to maintain separate the opposite air flows passing through saidinner and outer casings under the influence of said first fan wheel andsecond blade assembly, and damper means located beneath said secondblade assembly to control the said separate opposite air flows.

2. A contra-flow ventilating assembly as claimed in claim 1 wherein saiddamper means to control said separate opposite air flows comprisesdamper blades mounted within said inner and outer casings and means tocontrol said damper blades.

3. A contra-flow ventilating fan assembly adapted for use in industrialair circulating systems comprising, a first fixed cylindrical airconducting outer casing of constant diameter, a second fixed cylindricalinner casing of lesser diameter than said outer casing mounted to andconcentrically of said outer casing, said inner casing being of slightlylesser length than said outer casing and having one end disposed belowthe corresponding end of said outer casing, said inner casing end havinga peripheral portion of reduced diameter, a contra-flow fan bladeassembly mounted in axial alignment with and above said inner and outercasings, means to support said fan assembly, a fiat top plate and aninwardly tapering bottom collar of annular formation, said fan assemblyhaving a first fan wheel having fixed tapered fan blades extendingradially inwards between said fiat top plate and said inwardly taperingbottom collar of annular formation, and a second set of fan bladesmounted at the roots to said fan wheel annular collar so as to extendradially outwards therefrom and being inclined whereby when rotated withsaid fan wheel to cause a movement of air in a direction opposite tothat caused by said fan wheel blades, the outer diameter of said secondfan blade assembly being substantially equal to the outer diameter ofsaid first fan wheel and less than the inner diameter of said outercasing with the diameter of said fan wheel annular collar at the pointof said second fan blades attachment being slightly greater than thesaid reduced diameter portion of saidinner casing permitting freerotation of said second fan blade assembly within an annular spacebetween said inner and outer casings, driving means including a drivingmotor disposed above and connected to said first fan wheel, a fixedannular air flow deflecting means surrounding said fan wheel and havinga portion extending inwardly between the outer periphery of said fanwheel and the blades of said second blade assembly thereby being adaptedto maintain separate the opposite air flows passing through said innerand outer casings under the influence of said first fan wheel and secondblade assembly, and means to control the said opposite air flows.

4. A contra-flow ventilating assembly as claimed in claim 3 wherein saidmeans to control said opposite air flows comprises damper means withinsaid inner and outer casings and means to control said damper means.

5. A contra-flow ventilating fan assembly adapted for use in industrialair circulating systems comprising, a first fixed cylindrical airconducting outer casing of constant diameter, a second fixed cylindricalinner casing of lesser diameter than said outer casing mounted to andconcentrically of said outer casing, said inner casing being of slightlylesser length than said outer casing and having one end disposed belowthe corresponding end of said outer casing, said inner casing end havinga peripheral portion of reduced diameter, a contra-flow fan bladeassembly mounted in axial alignment with and above said inner and outercasings, means to support said fan assembly, a flat top plate and aninwardly tapering bottom collar of annular formation, said fan assemblyhaving a first fan wheel having fixed tapered fan blades extendingradially inwards between said fiat top plate and said inwardly taperingbottom collar of annular formation, and a second set of fan bladesmounted at the roots to said fan wheel annular collar so as to extendradially outwards therefrom and being inclined whereby when rotated withsaid fan wheel to cause a movement of air in a direction opposite tothat caused by said fan Wheel blades, the outer diameter of said secondfan blade assembly being substantially equal to the outer diameter ofsaid first fan wheel and less than the inner diameter of said outercasing with the diameter of said fan wheel annular collar at the pointof said second fan blades attachment being slightly greater than thesaid reduced diameter portion of said inner casing permitting freerotation of said second fan blade assembly within an annular spacebetween said inner and outer casings, a driving motor mounted above andin axial alignment with said fan blade assembly and having a drivingshaft directly connected to said first fan wheel, a fixed annular airflow deflecting means surrounding said fan Wheel and having a portionextending inwardly between the outer periphery of said fan wheel and theblades of said second blade assembly thereby being adapted to maintainseparate the opposite air flows passing through said inner and outercasings under the influence of said first fan wheel and second bladeassembly, and means to control the said opposite air flows.

6. A contra-flow ventilating fan assembly, comprising an annular base,spaced apart standards extending upwardly from said base incircumferentially spaced relationship, a first air conducting duct ofcylindrical formation mounted concentrically of said base, a second airconducting duct of cylindrical formation and of lesser diameter thansaid first duct mounted concentrically within said first duct in spacedrelation therewith, means to support said second duct within said firstduct in said spaced relation, an air deflecting member of annularformation having opposed outwardly and inwardly sloping flanges mountedon said standards in spaced concentric relationship With said base andabove the upper 7 ends of said first and second ducts, a motor mountingplate of circular outline mounted on said standards above and in spacedconcentric relationship with said annular air deflecting member, adriving motor mounted centrally of said motor supporting plate andhaving a driven shaft extending through an axial opening in said motorsupporting plate, a fan wheel having fixed tapering fan blades extendingbetween a flat top plate and an inwardly tapering bottom annular collar,said fan Wheel top plate being connected directly to said motor shaftextending concentrically from said motor mounting blade with said bladesadapted to cause a movement of air from the axes of said fan bladeassembly to the periphery in one direction, a further plurality of fanblades mounted at the roots to said fan wheel annular collar so as toextend radially outwards therefrom and being inclined when rotated withsaid fan wheel to cause a movement of air in a direction opposite tothat created by said fan Wheel, the outer diameter of said second fanblade'assembly being less than the inner diameter of said firstair-conducting duct with the diameter of said fan wheel annular collarat the point of said blade attachment being slightly greater than areduced upper portion of said second duct permitting free rotation ofsaid second fan blade assembly within the annular space between saidfirst and second ducts.

References Cited by the Examiner UNITED STATES PATENTS 2,004,571 6/35Bothezat 230-117 2,435,092 1/48 Meyer 2301l4 3,122,307 2/64 Wasson et al230l17 DONLEY J. STOCKING, Primary Examiner.

ROBERT M. WALKER, LAURENCE V. EFNER,

Examiners.

1. A CONTRA-FLOW VENTILATING FAN ASSEMBLY ADAPTED FOR USE IN INDUSTRIALAIR CIRCULATING SYSTEMS COMPRISING,, A FIRST FIXED CYLINDRICAL AIRCONNDUCTING OUTER CASING OF CONSTANT DIAMETER, A SECOND FIXEDCYLINDRICAL INNER CASING OF LESSER DIAMETER THAN SAID OUTER CASINGMOUNTED TO AND CONCENTRICALLY OF SAID OUTER CASING, SAID INNER CASINGBEING OF SLIGHTLY LESSER LENGTH THAN SAID OUTER CASING AND HAVING ONEEND DISPOSED BELOW THE CORRESPONDING END OF SAID OUTER CASING, ACONTRA-FLOW FAN BLADE ASSEMBLY, A FLAT TTOP PLATE AND AN INWARDLYTAPERING BOTTOM INNER AND OUTER CASINGS, MEANS TO SUPPORT SAID FANASSEMBLY, A FLAT TOP PLATE AND AN INWARDLY TAPERING BOTTOM COLLAR OFANNULAR FORMATION, SAID FAN ASSEMBLY HAVING A FIRST FAN WHEEL HAVINGFIXED TAPERED FAN BLADES EXTENDING RADIALLY INWARDS BETWEEN SAID FLATTOP PLATE AND SAID INWARDLY TAPERING BOTTOM COLLAR OF ANNULAR FORMATION,AND A SECOND SET OF FAN BLADES MOUNTED AT THE ROOTS TO SAID FAN WHEELANNULAR COLLAR SO AS TO EXTEND RADIALLY OUTWARDS THEREFROM AND BEINGINCLINED WHEREBY WHEN ROTATED WITH SAID FAN WHEEL TO CAUSE A MOVEMENT OFAIR IN A DIRECTION OPPOSITE TO THAT CAUSED BY SAID FAN WHEEL BLADES,MEANS SUPPORTING SAID INER CYLINDRICAL CASING CONCENTRICALLY OF ANDRELATIVE TO SAID OUTER CASING PERMITTING FREE ROTATION OF SAID SECONDFAN BLADE ASSEMBLY WITHIN AN ANNULAR SPACE BETWEEN SAID INNER ANND OUTERCASINGS, DRIVING MEANS INCLUDING A DRIVING MOTOR PARTITIONED FROM ANDMOUNTED DIRECTLY ABOVE SAID CONTRAFLOW FAN ASSEMBLY WITH A CONNECTION TOSAID FIRST FAN WHEEL, A FIXED ANNULAR AIR FLOW DEFLECTING MEANSSURROUNDING SAID FAN WHEEL AND HAVING A PORTION EXTENDING INWARDLYBETWEEN TTHE OUTER PERIPHERY OF SAID FAN WHEEL AND THE BLADES OF SAIDSECOND BLADE ASSEMBLY THEREBY BEING ADAPTED TO MAINTAIN SEPARATE THEOPPOSITE AIR FLOWS PASSING THROUGH SAID INNER ANNND OUTER CASINGS UNDERTHE INFLUENCE OF SAID FIRST FAN WHEEL AND SECOND BLADE ASSEMBLY, ANDDAMPER MEANS LOCIAT ED BENEATH SAID SECOND BLADE ASSEMBLY TO CONTROL THESAID SEPARATE OPPOSITE AIR FLOWS.